Clara finds this book inside the library in Journey to the Centre of the TARDIS. However, at the end of the Time War, everybodys dead so nobody could have written a history of it. Although it could end with the writer writing that there was a strange rumbling sound in the distance... But what if it was written by the Doctor? Specifically the War Doctor, who could be compiling it as a way to never let himself forget what he did, and to always let the universe know of the horrors of what happened. At the end of his adventure with Churchill, he would sit down and catalogue it all. He could also use a TARDIS diary since he already owned at least two. It would explore the good side of the War Doctor, one which was never fully explored to its full potential in the show.